CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	Common Class A [Member]	Common Class B [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Opening Balance VALUE at Dec. 31, 2010	$ 170,667	$ 307	$ 74	$ 592,643	$ (415,080)	$ (7,277)
Opening Balance SHARES at Dec. 31, 2010		30,700,568	7,367,532
Conversion of Class B common stock to Class A common stock SHARES		170,000	(170,000)
Compensation expense related to granting of stock options SHARES		0	0
Compensation expense related to granting of restricted stock units SHARES		416,906	0
Issuance of common stock related to an incentive plan SHARES		0	0
Common stock repurchase SHARES		0	0
Exercise of stock options SHARES		53,625	0
Purchase of vested employee restricted stock units SHARES		(297,098)	0
Net income (loss)	68,510	0	0	0	68,510	0
Conversion of Class B common stock to Class A common stock VALUE	0	2	(2)	0	0	0
Compensation expense related to granting of stock options VALUE	462	0	0	462	0	0
Compensation expense related to granting of restricted stock units VALUE	7,209	4	0	7,205	0	0
Issuance of common stock related to an incentive plan VALUE	0	0	0	0	0	0
Common stock repurchase VALUE	0	0	0	0	0	0
Purchase of vested employee restricted stock units	(3,057)	(3)	0	(3,054)	0	0
Forfeitures of dividend equivalents VALUE	5	0	0	0	5	0
Realization of tax benefit for dividend equivalent payments VALUE	0	0	0	0	0	0
Exercise of stock options VALUE	71	0	0	71	0	0
Net unrealized gain (loss) on derivatives VALUE	7,277	0	0	0	0	7,277
Ending Balance VALUE at Dec. 31, 2011	251,144	310	72	597,327	(346,565)	0
Ending Balance SHARES at Dec. 31, 2011		31,044,001	7,197,532
Conversion of Class B common stock to Class A common stock SHARES		0	0
Compensation expense related to granting of stock options SHARES	0	0	0
Compensation expense related to granting of restricted stock units SHARES		275,042	0
Issuance of common stock related to an incentive plan SHARES		0	0
Common stock repurchase SHARES		0	0
Exercise of stock options SHARES	(66,600)	66,600	0
Purchase of vested employee restricted stock units SHARES		(71,692)	0
Net income (loss)	(4,256)	0	0	0	(4,256)	0
Conversion of Class B common stock to Class A common stock VALUE	0	0	0	0	0	0
Compensation expense related to granting of stock options VALUE	123	0	0	123	0	0
Compensation expense related to granting of restricted stock units VALUE	2,595	3	0	2,592	0	0
Issuance of common stock related to an incentive plan VALUE	0	0	0	0	0	0
Common stock repurchase VALUE	0	0	0	0	0	0
Purchase of vested employee restricted stock units	(474)	(1)	0	(473)	0	0
Payments of dividends VALUE	0	0	0	0	0	0
Forfeitures of dividend equivalents VALUE	9	0	0	0	9	0
Exercise of stock options VALUE	89	1	0	88	0	0
Net unrealized gain (loss) on investments VALUE	0	0	0	0	0	0
Net unrealized gain (loss) on derivatives VALUE	0	0	0	0	0	0
Ending Balance VALUE at Jun. 30, 2012	$ 249,230	$ 313	$ 72	$ 599,657	$ (350,812)	$ 0
Ending Balance SHARES at Jun. 30, 2012		31,313,951	7,197,532